Re: Billy Goat Trail section A, is the actual hike free? If not, what's the entrance fee?
And what's good about the hike? Scenery? Do you see animals too, like deers, "goats" n stuff??
The hike itself is free but you must pay for parking in the main lot. If you arrive early enough or if you go during the week you may find parking in a different lot which is free. Main lot is by Great Falls Visitors Center, free lots are
across the street from the Old Anglers Inn (do not park in the Inn's lot).
This is the most popular hike in the DC area and can sometimes get crowded but it is well worth it. The are no large animals on it, it is called the Billy Goat Trail because it makes you feel like a billy goat as you hop from rock to rock. It is really fun and slightly difficult but not as hard as the website makes it seem. Most 8 year olds can do it and I once went with a 5 year old (I wouldn't recommend bringing most kids this young).
There is almost no boring walking on this hike except for at the beginning and end getting to and from the trailheads. Most of the time you are overlooking the Potomac river so it is quite scenic but the main attraction is the "rock scrambling"; climbing from rock to rock, occasionally using your hands to climb up or down.
I have never done sections B or C but they are supposed to be much less difficult, less popular, and less fun.
Feel free to PM me for more detailed directions and descriptions (you can also Google it as there is a lot of information about it online).
ETA: The hike itself is 1.7 miles plus a mile or more getting to and from the trail (alternatively you can hike both ways on the trail) so it should take between 1-2 hours.